Electrical condenser



Patented Aug. 1s, 1.925.

WILLIAM W. DODGE, -J'R., OF MERIDEN, CONNECTICUT.

ELECTRICAL CONDENSER.

Application filed October 19, 1922. Serial No. 595,607.

To all whom it may concern:

Be it known that I, VVILLIAM W. Donen, Jr., a citizen of the United States, residin at Meriden, in the county of New Haven and State of Connecticut, have invented certain new and useful Improvements in Electrical Condensers, of which the following is a specification.

This invention relates to variable condensers, and particularly to means for producing fine adjustments of capacity.

The usual fine adjustment condenser in cludes a large variable condenser unit which gives a coarse adjustment of capacity, and

a related smaller variable condenser which gives a finer adjustment. In the use of such condensers thelarge condenser is first adjusted to give approximately the correct capacity and the final adjustment is then made by manipulating the small condenser, which permits more precise adjustment because a relatively large movement produces a relatively small change of capacity.

The object of the present invention is to permit the two adjustments to be made by successive manipulations of a single knob or actuator and the result is secured by connecting the actuator ,to the small unit positively and providing a'lost motion connection between these and the large unit, so that the actuator. may be turned in one direction to engage the large unit, and by continued movement in this direction will then adjust both units in unison. Reverse movement of 5 the actuator within the limits of the lost motion will then produce a relatively negative adjustment of the small unit only.

Starting, for example, with both units set at zero the two units are adjusted by the actuator together until best effect is reached and slightly passed, then a reverse movement of the actuator makes a final subtractive adjustment by the small unit alone.

' The inventionmay be embodied in various types of adjustablecondenser, and is shown in the accompanying drawing as embodied in that type in which two sets of sector plates are movable into and out of interleaved relation with a fixed set of sector plates. This is the preferred arrangement because concentric shafts and consequently a very simple lost motion connection become posslble.

In the drawing Fig. 1 is a plan view of the complete conas denser, a part of the cover being broken away to show the construction. j

Fig. 2 is a vertical axial section, a portion being broken away to simplify the drawing.

Fig. 3 1s a fragmentary perspective view no showing the stop mechanism interposed between the two dials and hence between the two movable elements of the condensers.

The condenser is constructed with back plate 6, cylindrical shell 7, cover ring 8 and M5 a spider 9, all preferably formed of dielectric material. The mode of connecting these parts together is only partially shown in the drawing, as such details are not features of the invention. The spider 9 is made separate from the ring 8 for convenience in assembling the device and is provided at its center with a bearing 10 which supports one end of the adjusting sleeve and shaft.

Extending between the back plate 6 and the cover ring 8 are a plurality of posts 11 formed of conducting material, for example aluminum, and ofi'erlng support to a series of arcuate fixed plates 12 which, in the example shown, subtend an angle of 180. These plates are spaced apart to offer intervals for the insertion of movable plates, as is familiar to those skilled in the art. A post 13, similar in form and arrangement to the posts 11, receives the connecting strips 14: and 15 through which anelectrical connection is made to the movable plates hereafter described.

In the center of the back plate 6 there is mounted a threaded bushing 16 which receives a pivot screw 17 A look nut 18 serves; the double purpose of locking the screw 17 in adjusted position and providing good conducting contact with the strip 15. A shaft 19 is pivoted at one end on the pivot screw-17 and carries near this end a movable condenser plate 20 which is-clamped on the shaft 19 between the nuts 21 threaded thereon. One nut 21 bears against a washer 22 which in turn is seated against the end of a tubular shaft or quill 23.-

The shaft 23. surrounds the shaft 19 and turns in the bearing 10 formed in the s ider 9. A collar 24: formedon the shaft 23 ears against a spring washer 25 and this in turn bears against the conducting strip 14 which transmits the thrust to the spider 9. Thus the thrust of the pivot screw 17 is taken by the spider 9 and tends to maintain electrical contact between the shaft or quill 23 and the connecting plate 14.

Below thev collar 24 a plurality of sectorshaped plates 26 are assembled with intervenmg spacers or rings 27 These plates subtend an angle of 180 and the spacers are so dimensioned as to cause the plates 26 to swing in the intervals between successive plates 12. The plates and the spacers are clamped on the quill 23 by. means of the nut 28. i

The dial 29 is fixed to the quill 23 by meansof a set screw. On its upper face, the dial 29 is formed with a circular recess and at the periphery of this recess there is formed a notch 30 whose ends serve as stops for an upstanding lug 31 carried by an arm 32 which swivels freely on the shaft 19.

A second dial 33 is mounted in the central recess of the dial 29 with its upper face flush with the upper faceof the dial 29. The dial 33 is fixed on the. shaft 19 by means of a set screw and carries at its periphery a projecting lug 34: which swings over the upper face of dial 29 in position to engage the lug 31.

The notch 30 and the lugs 31 and 34 are so proportioned that dial 33 may have exactly 360 of rotation relatively to dial 29, and the lugs are so positioned relatively to the plates that at the opposite limits of motion the rotatable plates of the two sets are in register, i. e., are similarly adjusted relatively to their corresponding fixed plates.

Theshaft 19 may be turned by means of a knob 35.

The electrical connection to the movable plates is made through a lead 36 connected by a screw to the post 13, as shown, and in this way to the connecting plates 14 and 15.

The electrical connection to the fixed plates is made through a lead 37 connected by a screw to one of the posts 11.

In order to secure indicating dials which will read decimally, I prefer to make the capacity of one condenser ten times that of the other and then graduate the dials 29 and 33 so that one graduation on the dial 29 is equivalent to ten graduations on the dial 33. The readings of both dials are read against a fixed index 38 on the cover ring 8.

To prepare the condenser for adjustment the knob 35 is turned in one direction, say to the right, until the'dial 33 picks up the dial 29, and this rotation is continued until dial, the two condenser units are adjusted together until the desired graduation on the dial 29 is exactly opposite the index 38. Reverse movement of the knob 35 effects the desired fine adjustment, and the numbers onv the two dials, read consecutively, indicate the total capacity. This holds true except in adjustments where the smaller condenser is set to its maximum capacity. In this case its reading 10 indicates that one should be added to the reading on the dial 29.

'Where the dial indications are not needed, for example where the condenser is connected as a part of a radio receivin set, the knob 35 is turned to the right until the dial 29- is picked up, and the rotation is continued until the best effect is reached and slightly passed. Thereupon a slight reverse movement of the knob 35 will produce a negative adjustment of the smaller condenser. This adjustment brings the capacity back to that suitable for best efiect and can be made with precision because a relatively,

large movement of the knob produces a relatively small change in capacity.

While I prefer the decimal arrangement of the dial above described, it is possible to make slightly different arrangements using different numbers of plates, and I do not limit myself in this regard, except as expressly stated in the claims.

While I prefer to embody the device in a condenser in which the adjustable elements are rotated, for the reason that this simplifies the construction and manipulation, the invention is applicable to other types of adjustable condenser. It is not necessarily limited to the rotary type.

What is claimed is 1. The combination of two condensers having individually movable means for adjusting their respective capacities; an actuator; a positive connection between the actuator and the adjusting means of one condenser; and a lost motion connection between the actuator and the adjusting means of the other condenser, such lost motion being equal to the entire range of adjusting motion of the first condenser.

2. The combination of two condensers each having plates rotatable to vary the capacity of the corresponding condenser, the capacity of each condenser varying pro gressively from zero to its maximum and back to zero in 360 degrees of rotation; actuating means positively connected to rotate the plates of one of said condensers; and a connection between said actuator and the rotatable plates of theother condenser positively connected with the rotatable arranged to permit 360 degrees of lost plates of one condenser; and a connection 10 motion. between said actuator and the rotatable 3. The combination of two condensers plates of the second condenser arranged to 5 having fixed plates and rotatable plates Permit d g es f 1 81 1 1 subtending approximately 180 degrees each, In g ny l Q I have slgned y the rotatable plates of the two condensers name to thls "Speclficatlonbeing mounted on aligned axes; an actuator WILLIAM W. DODGE, JR. 

